Condenser



May 19, 936- M. H. BENNETT 2,041,280

CONDENSER Filed Aug. 50, 1934 I 2 Sheets-Sheet l v \n\\\\\\\\\\ -& J I6I 15 a W 9ATTORNEYS May 1936- M. H. BENNETT 2,041,280

CONDENSER Filed- Aug. :0, 1954 2 Sheets-Sheet 2' lNVE OR Patented May19, 1936 CONDENSER Morris H. Bennett, Prospect, Conn, assignor toScovill Manufacturing Company, Waterbury, Conn., a corporation ofConnecticut Application August 30, 1934, Serial No. 742,059

4 Claims.

densers.

An object of the invention is to provide a variable condenser in whichthe rotor and stator 5 plates are in permanent predetermined spacedrelation to each other, and in which this result is secured by a novelmethod of constructing the condenser, this being accomplished withoutthe use of screws or other adjusting means. in Another object of theinvention is to provide a condenser and method of constructing it whichwill lower the cost of manufacturing.

Another object is to provide a novel rotor plate unit and novel meansfor insulatably and perl-w manently securing this unit to the rotorshaft.

A further object of the invention is to provide, in connection with therotor plate unit, a trimmer condenser carried by the frame, one of whoseplates is provided with one or more arms making wiping contact with therotor plate assembly throughout its range of movement.

Still further objects and advantages of the invention will appear fromthe following description taken in connection with the accompanyingdrawings, which illustrate a preferred embodiment of the invention, andin which:

Fig. l'is a top plan view of the preferred embodiment;

' Fig. 2 is aside elevation thereof; Fig. 3 is a transverse sectiontherethrough;

Fig. 4 is an enlarged fragmentary sectional view showing part of therotor plate unit and its insulated permanent attachment to the rotorshaft; V Fig. 5 is a top plan view, partly in horizontal section,showing the trimmer condenser and its wiping contact arms; Fig. 6 is afragmentary vertical transverse sectional view showing in further detailthe trimmer condenser structure of Fig. 5, and 40 Fig. '7 is afragmentary transverse sectional view through the rotor shaft showingthe mounting for it in one of the condenser frame ends.

Referring in detail to the drawings, a condenser frame has front andrear end plates l2 and I4, respectively, and side plates l6 having anintegral bottom portion l8. provided with suitable openings 20 for theinsertion of the spacing combs hereinafter referred to.

The sides and bottom are provided with slotted I re-entrant portions 22,in which are placed a plurality of stator plates 24, the edges of thestator plates protruding through the slots being staked over to lock thestator plates permanently and rigidly in predetermined desired relation.

In accordance with'the invention, a rotor plate The present inventionrelates to variable con-,

unit is provided and includes a plurality of rotor plates 28. Inassembling the rotor plate unit, the rotor plates are properlypositioned in an assembly jig and a tie bar 3!! placed in position witha plurality of tongues 32 on each'- rotor plate pro- 5 acting throughslots in the tie bar. The tongues are then staked over and the rotorplates of the unit are thereby rigidly and permanently held in desiredspaced relation.

The rotor plate tie bar 35 has a channel por- 10 tion 34 fitting thecurved cut-outs in the rotor plates, and, as shown in'the drawings, eachrotor plate is provided with three tongues staked to the tie bar channelport-ion and with two tongues staked to the flat part of the tie barextending 15 along-the upper edges of the rotor plates.

This structure, constituting the rotor plate unit, is placed in theframe .with the rotor plates properly interleaved with the statorplates. accurate interleaving being insured by the use of spacing g0,combs insertible through openings 20, or by other desired means, andwhile so held the rotor shaft is placed in position in the frame.

The rotor shaft is provided with a plurality of passages extendingdiametrically through it and 25 in alignment with each other. Theseholes are counterbored for the reception of cylindrical porcelainwashers 38. A bridge plate or assembly plate 40 has. a seating pocketfor a second porcelain washer 42. The porcelain washer seats in 30 theshaft and in the assembly plate are deep enough to receive the washersup to about half the height of the washers, and when the assembly plateand washers are in position, a rivet or eyelet is inserted through thewashers and through an 35 opening in the washer seat of the assemblyplate slightly" greater in diameter than the rivet or eyelet. The rivetor eyelet 46 extends through the 'shaft opening and is then closed overat both ends (Fig. 4), thus providing an exceptionally 4o rigidconstruction with excellent electrical insulation. I

The shaft carrying the assembly plate is placed in the condenser frameand is preferably assembled therein so that it cannot moveaxlally. As 4,indicated in Fig. 4, the assembly plate 40, carried by the shaft, lieswithin the channel portion 34 of the rotor plate tie bar.

At its forward end the rotor shaft 4| has fixed to it a disc 50 havingtwo stop shoulders 52 and 50' 53 to limit the rotation of the shaft ineither direction by contacting a lug 54 punched out of the end plate l2.The disc 50 serves to retain the balls 56 in their raceway 5B in thefront end plate and to prevent movement of the rotor shaft axialll ly tothe right as viewed in Fig. 1. A pointed pressure screw ill, carried bythe rear end plate ll, supports the other end of the shaft and preventsit "from moving to the left.

While the rotor plate units are held in interleaved position by combs orotherwise, the assembly plate 40 is soldered along its upper edges,

' as at 65, to the rotor plate tie bar 30 along both means that canpermit the destroying of this adjustment by vibration or otherwise.Moreover, it will be noted that expensive adjusting operations areeliminated.

Referring to the trimmer construction, the frame side It is providedwith an opening II, in which is inserted the lower end of a flexiblemovable trimmer condenser plate 14, whose upper end is movable towardand from a fixed trimmer condenser plate It by adjusting nut 18 on ascrew 80 carried by the frame side plate. The fixed plate 16 bears onan-insulator 82 between itself and the frame side I 6 and is providedwith an opening through which the screw 80 extends. A sheet of mica 84,or similar material, is located between the fixed and movable plates ofthe trimmer condenser. The fixed plate 16 is provided with attachingportions 88 passing through openings in the insulator 82 and bent overto lock the fixed plate in position as shown in Pig. 5.

At each end the fixed plate 16 is provided with a flexible arm 90 havinga turned-up end 92 bearing on an edge of the channelportion 34 of therotor ,tie bar. The fixed plate 16 is also provided with a pair of ears94 which may be used as $01- derin'g lugs to make the connection. Itwill be noted that the wiper arms 90 conduct energy from the rotordirectly to the trimmer plate I8;

that a minimum of insulation is employed; and

- that the movable plate 14, being grounded, acts as a shield to preventstray electrostatic fields from adjacent trimmers afl'e'cting eachother. Moreover, it will be seen that there are no joints between thewiper arms 90 and fixed trimmer plate 16 to become defective or toloosen and cause poor connection, leading, in a radio set, to consequentnoise. Also, the inductance of the wiper arms is constant regardless ofthe position of the rotor unit.

What is claimed is:

1. In a condenser, and in combination, a rotor unit comprising aplurality of rotor plates, 8. tie

bar to which the several rotor plates are rigidly .secured, a rotordrive shaft, an assembly plate secured in fixed integral metallicrelation to said tie bar, an insulating washer between the shaft andsaid assembly plate, a second insulating washer on the opposite side ofthe assembly plate, the assembly plate having an opening and the shafthaving a diametrical bore in line with said washers, and a rivet passingthrough said bore, opening and washers and headed over at its ends tosecure the shaft and assembly plate together in rigid and insulatedconnection.

2. In a condenser, and in combination, a rotor unit comprising aplurality of rotor plates having arcuate cut-outs about the shaft, a tiebar having a flat portion and a channel portion corresponding to saidcut-outs, a plurality of tongues on each of said rotor plates extendinginto openings in the tie bar and staked over therein, an assembly platebridging and soldered to the channel portion of the tie bar, and meansfor rigidly connecting the shaft to-said assembly plate.

3. In a condenser, and in combination, a rotor unit comprising aplurality of rotor plates having arcuate cut-outs about the shaft, a tiebar having a flat portion and a channel portion corresponding to saidcut-outs, a plurality of'tongues on each of said rotor plates extendinginto openings in the tie bar and staked over therein, an assembly platebridging and soldered to the channel portion of the tie bar, aninsulating washer between the shaft and said assembly plate, a secondinsulating washer on the opposite side of the assembly plate, theassembly plate having an opening and the shaft having a diametrical borein line with said washers, and a rivet passing through said bore,opening and washers and headed over at its ends to secure the shaft andassembly plate together in rigid and insulated connection.

4. The herein described method of assembling the parts of a condenser inpermanent adjusted relation which comprises rigidly and permanentlysecuring the stator plates in a frame, rigidly and permanently securingthe rotor. plates to a tie bar, interleaving the rotor plates with thestator plates, inserting temporary spacing members between the two setsof plates to eifect predetermined spacing, mounting the shaft in theframe and confining it against axial movement, and, while the temporaryspacing members are still in place, rigidly and permanently securing theshaft to the tie bar.

MORRIS H. BENNE'I'I

